Change List for this Rule

 

General Order 95

 

Section IV

 

Strength Requirements for All Classes of Lines

49.1     Poles, Towers and Other Structures

 

A.      Strength

 

(1)       Wood poles shall be of sound timber,and shall meet the following:

 

a)       Temperature and loading factors as specified in Rule 43.

 

b)       Safety factors not less than those specified in Rule 44,. and the modulus of rupture used in calculation of safety factors per Rule 48.1.

 

(2)       Non-wood poles, towers and structures, including their foundations, shall meet the following:

 

a)       Temperature and loading factors as specified in Rule 43.

 

b)       Safety factors not less than those specified in Rule 44, and the structural values used iin calculation of safety factors per Rules 48.2, 48.3 and 48.6.

 

(3)       In cases where lateral stresses on a pole or structure require the use of a guy(s), the pole or structure below the point of the guy attachment shall be considered merely a strut, the guy(s) taking all lateral stresses. In such cases, the pole strength requirement shall apply at the point of guy attachment rather than at the ground line.

 

(4)       Crossing spans - for crossing spans, spliced or stub reinforced poles or pole top extensions, including the attachment (joint) of the different members involved, shall meet all of the vertical, transverse and longitudinal strength requirements of these rules as if a whole pole were used.

 

Note:      Revised July 26, 1966 by Decision No. 71009 March 30, 1968 by Decision No. 73813 February 13, 1974 by Decision No. 82466 January 21, 1992 by Resolution SU–10. and  January 13, 2006 by Decision No. 05-01-030

 

B.      Dimensions

 

The minimum top circumference of wood poles shall be not less than the following:

 


Inches

Grade “A” Heavy loading district

22

Grade “A” Light loading district

19

Grade “B” * Heavy and light loading districts

19

Grade “C” Heavy and light loading, urban districts

19

Grade “C” Circuits of 750-7,500 Volts, heavy loading, rural districts

19

Grade “C” Supply circuits of 0-750 Volts and communication circuits, heavy loading rural districts

16

Grade “C” Light loading, rural districts

16

Grade “F” Cable or more than 4 single wires or 8 conductors duplexed or paired, heavy loading districts

15

Grade “F” Cable or more than 6 single wires or 12 conductors duplexed or paired, light loading districts

15

Grade “F” Not more than 4 single wires or 8 conductors duplexed or paired, heavy loading districts

12

Grade “F” Not more than 6 single wires or 12 conductors duplexed or paired, light loading districts

12

 

Note:      Poles having a ground line circumference of less than 12 inches are not safe to climb unless supported by guys, pike poles, etc.

 

*      Supply Poles in Grade “B” construction in rural, light loading districts may have a top circumference less than 19 inches but not less than 16 inches.

 

*      Communication Poles in Grade “B” construction at crossings over major railroads may have top circumferences less than 19 inches but not less than the following, provided such poles meet the specifications of the American Standards Association, 05.2–1941, 05.4–1941 or 05.6–1941, and are butt treated if of western red cedar or are full–length pressure treated if of Douglas fir or Southern Yellow pine:

 

Number of Conductors Supported

Minimum Pole Top Circumference (inches)

Heavy Loading

Light Loading

10 or less

15

15

11-20

17

17

21 -40

19

17

More than 40

19

19

 

C.      Setting of Poles

The depths of pole setting given in
Table 6 are applicable to wood poles set in firm soil or in solid rock. Where the soil is not firm, deeper settings or other special methods of pole setting should be used. Where unguyed poles are set subject to heavy strain, or at corners or curves, deeper settings or other special measures to prevent overturning or excessive movement of the pole at the ground line should be used.     Where poles were set in firm soil, but the soil has since been excavated or subjected to minor ground erosion, the measure setting depth shall remain within 10% of the minimum values specified in Table 6, columns 2 and 3.
 
Metallic poles, prestressed concrete poles, or poles of other non–wood materials that are set directly in firm soil or rock shall be set at least as deep as specified in Table 6 for wood poles. Where the resultant bearing surface of these poles is not sufficient to prevent overturning or excessive movement of the pole at the ground line under maximum loading conditions, special measures such as heel and toe bracing, setting in concrete, bolting to a concrete foundation, or other special methods shall be used.

 

Note:      Revised July 26, 1966 by Decision No. 71009, February 13, 1974 by Decision No. 82466, January 19, 1994 by Resolution SU–25, October 9, 1996 by Resolution SU–40 and  January 13, 2006 by Decision No. 05-01-030

 

Table 6: Pole Setting Depths of Wood Poles

Total Length of Pole (feet)

Depth in Soil (feet)

Depth in Rock (feet)

20

4

3

25

4 1/2

3

30

5

3

35

5

3 1/2

40

5 1/2

3 1/2

45

6

4

50

6 1/2

4

55

7

4 1/2

60

7

4 1/2

65

7 1/2

5

70

7 1/2

5

75

8

5 1/2

80

8

6

 

Note:      Revised March 9, 1988 by Resolution E–3076

 

D.      Gains

Gains or equivalent means shall be provided for increasing surface contact of crossarms with round wood poles. Where gains are cut, the depth shall be not less than one–half inch or more than one inch. “Slab” gains, metal gains, pole bands, or assemblies of wood or metal supports that provide suitable surface contact and adequate strength are permitted.

 

E.      Replacements (See Rule 44.3 )